!UPSTREAM: Interface Blocks: Test how interface block members are accessed from API

v2: Add checks to also test invalid names

v3 (Paul Berry <stereotype441@gmail.com>): use piglit_link_check_status_quiet()

TODO:
- Let Nick push this.
!UPSTREAM: mess with all.tests
Escape HTML output when generating test result pages.

If a test generates output containing '<', '>', or '&', we need to
HTML escape it so that the web browser doesn't interpret it as
containing HTML tags.

While we're at it, go ahead and HTML escape the traceback and dmesg
outputs too.